docs: def is_multi_timeseries_orthogonal(nc, variable):
      '''
      Returns true if the variable is a orthogonal multidimensional array
      representation of time series. For more information on what this means see
      CF 1.6 §H.2.1
  
      http://cfconventions.org/cf-conventions/v1.6.0/cf-conventions.html#_orthogonal_multidimensional_array_representation_of_time_series
  
      :param netCDF4.Dataset nc: An open netCDF dataset
      :param str variable: name of the variable to check
      '''
      # x(i), y(i), z(i), t(o)
      # X(i, o)
      dims = nc.variables[variable].dimensions
  
      cmatrix = coordinate_dimension_matrix(nc)
  
      for req in ('x', 'y', 't'):
          if req not in cmatrix:
              return False
      if len(cmatrix['x']) != 1 or cmatrix['x'] != cmatrix['y']:
          return False
      if 'z' in cmatrix and cmatrix['x'] != cmatrix['z']:
          return False
  
      timevar = get_time_variable(nc)
      if cmatrix['t'] != (timevar,):
          return False
  
      i = cmatrix['x'][0]
      o = cmatrix['t'][0]
      if dims == (i, o):
          return True
      return False